All-in-One - Internal Display shows backlight only with no image - HDMI works

[DougBateman3212]

All in One Desktop PC - When I turn it on, the backlight turns on the display and the power light comes on. I found that it boots properly when I connected the HDMI. No image on the internal display at all. 

Have replaced the motherboard, and the display already but same result with original motherboard and new display, original display and new motherboard, new motherboard and new display. Also replaced the LCD flex cable as well.

HDMI does not respond until Windows boots up so I am unable to access the BIOS/UEFI either.

[WAWood]

@DougBateman3212 

I can understand this must be pretty frustrating situation -- but no one has responded to you before this simply because there is nothing we can do for you from here.  We have no access of any kind to your PC and we do not provide hardware diagnostics or troubleshooting support.

Yes, what you have done SHOULD work -- but we here have no technical information to assist you in finding out why it does not.

You can try taking this to an HP service facility, but my guess, since you have removed the basic components, is that they will simply refuse to even look at it.

Since you live in the U.S., here is a link to the HP Service Repair Centers:
https://www.service-center-locator.com/hp-hewlett-packard/hp-hewlett-packard-service-center.htm

If that link does not provide you sufficient information, then use the main HP link:
https://support.hp.com/us-en/contact-hp?openCLC=true

I've found those links to be unreliable if you're using Win10 and the new Edge Browser; so if you are, you need to use something else, like FireFox.

Good Luck